In general, a spring tube is a core component for an air suspension system and serves to reduce a damage of a car body and provide a comfortable ride to a passenger by connecting a car axle and the car body with each other by pneumatic pressure to thereby properly reduce vibration or shock transferred from the surface of the road during drive, so as to adjust a buffer power according to drive conditions and provide smoother feeling of drive by adjusting pneumatic pressure.
Moreover, the spring tube is mounted between a lower housing fixed to the car axle and an upper housing fixed to the car body, and provides buffering action by being filled with compressed air. Here, the spring tube is manufactured through the steps of inserting spring tube materials, which are stacked in multiple layers, into a melting machine and performing compression molding at high temperature, and in this instance, the spring tube is determined in buffering force and product quality by cords arranged inside in a mesh form.
However, the stacking and winding process of the spring tube materials depends on a worker's skill level, and hence, it makes a great difference in buffering force and product quality of the spring tube because an intersection angle of the cords is not exactly arranged at a preset angle.
Moreover, in order to wind the spring tube materials into a cylindrical form, a plurality of spring tube materials are stacked and wound in order on a winding roller, and the stacked and wound spring tube materials are separated from the winding roller, and are transferred to the high-temperature melting process. In this instance, the stacked and wound spring tube materials get in close contact with the winding roller, and hence, they are not easily separated even after the stacking and winding process is finished. Accordingly, when the worker forcedly pulls and separates the spring tube materials, the arranged angle of the spring tube materials is varied, and it causes poor quality of products,